A variety of linkage devices have been developed in the prior art for joining forklifts with auxiliary implements of various kinds. Such devices are intended to eliminate the need to have a number of separate wheeled vehicles (or trucks) for equipment performing different tasks.
Some examples of prior forklift linkage devices are disclosed in U.S. Pat. Nos. 4,243,354 (Garcia), 2,873,873 (Fowler), 2,364,493 (Ulinski), 3,788,492 (Kraft), 3,258,146 (Hamilton), 4,318,661 (Laken) and 4,065,013 (Orthman).
Each of these prior devices is engagable with the forwardly-extending tines of a forklift fork of the type movable vertically along the erect forklift slide frame structure, which will be referred to herein as a standard. Many such devices of the prior art provide an inadequate interengagement with the forklift for heavy work of various kinds.
For example, if heavy digging and scraping is done by the auxiliary equipment attached to a forklift, there can be a tendency for the linkage device to disconnect or be pulled off the fork tines. This tendency would exist if the auxiliary equipment is a backhoe, since such equipment does its work at such a distance from what would be the point of attachment to the forklift. And, when a substantial weight is to be carried at a distance by the auxiliary tool, a firmer interengagement between auxiliary tool and forklift is required than has been provided by devices of the prior art.
Some prior art devices engage the fork tines at a disadvantageous position. It is highly preferred to apply the work or loading pressure of the auxiliary tool or equipment onto the forklift as close to its center of gravity as possible and at as low a position as possible. The devices of the prior art have not been satisfactory in this regard.
One practice widely used in the prior art for installation of implements on forklift trucks involves the removal of the fork or, in some cases, of the fork and the standard along which it travels. This process is cumbersome and time consuming. However, the tine-engaging devices of the prior art have been inadequate substitutes for the reasons given above.
It is clear that there is a need for a simple and effective forklift linkage device of the type engageable with the forklift tines.